23rd century

The 23rd century, defined in the calendar of Earth as being from 2201 until 2300, was a period of expansion for the Federation, with Humans and other founding species, such as Vulcans, at the forefront of exploration. The long-running conflict with the Klingons, begun in the 22nd century, was a major topic of this century's history, as was the rekindling of tensions with the Romulans. Of particular note are the voyages of the starshipEnterprise and the careers of its long-serving command staff under James T. Kirk.

An alternate approach to the transporter, the Elway Theorem, is first tested in this century. Instead of utilizing subspace as the medium for which matter and energy are transported from one location to another, this form of transporting uses dimensions of space. In the end, this approach is rejected as fatal for the subject and being not as nearly as accurate as the transporter. (TNG: "The High Ground")

Late 23rd century to Early 24th century: Sometime between 2267 and 2270, Spock becomes commander-in-chief of the Terran Empire and implements several major reforms, turning the Empire into a more peaceful and less aggressive power. Prior to the full enactment of these reforms, the Terran Empire forces occupy Bajor. Spock's reforms leave the Empire unprepared to fight against the Klingon-Cardassian Alliance. The Alliance conquers the entire Terran Empire, enslaving the Terrans and Vulcans. (DS9: "Crossover")